Known filtration devices comprise:
at least two orifices, respectively a suctioning orifice for the water and a recirculating orifice for the filtered water,
at least three hydrocyclones, each forming a cyclonic filter capable of separating the water from solid particles contained in this water, said hydrocyclones being arranged in a circle to delimit a substantially cylindrical internal space which extends along a central axis.
Hydrocyclones have a frustoconical shape and use centrifugal force to separate the solid particles from the water. “Frustoconical shape” is understood in this case as a shape having a frustoconical part and possibly a cylindrical part. The water is introduced into each hydrocyclone via a tangential inlet orifice which communicates a rotational movement thereto which produces the centrifugal force. This centrifugal force separates the solid particles from the water and forces the solid particles along the wall of the cone. The solid particles are then driven toward the bottom of the hydrocyclone. The water, having had the solid particles removed, rises to the top of the hydrocyclone.
Such devices are disclosed, for example, in the patent application WO2008155649. They require the use of a pump to introduce the water into the hydrocyclones, and thus pipes connecting the pump to the device. Frequently, the pump is placed in an equipment container or pool equipment room located in the vicinity of the swimming pool. The combined unit of the pump and the filtration device thus takes up a large amount of space. Moreover, pressure losses are considerable in the pipes connecting the pump to the device.
The prior art is also known from: DE 19849870A1, WO2004026486A1, DE3539483A1 and WO2008155649A1.